DESCRIPTION: This investigator has made significant contributions to the understanding of cytokinesis. The mechanisms responsible for completing cytokinesis remain poorly defined. During the current period of support the applicant performed a genetic screen to identify novel proteins involved in cytokinesis. Two genes were identified. The first is racE, a small GTPase that appears to be an important signalling molecule required for cytokinesis. The second gene, called lvsA, has homology to the murine beige and the human FAN proteins, and is also required for cytokinesis. The current application builds on these findings with aims to dissect the role these two genes play in cytokinesis. Three specific aims are proposed: (1) to determine the role racE plays in cytokinesis, (2) to determine what other molecules interact with racE, and (3) to determine the role lvsA plays in cytokinesis.